Round the end of shape (mesh)
The bevel of a curve can be given a Taper Object in its 'Data' tab &gt; 'Geometry' panel:

The radius of the bevelled curve is varied according to the Y of the taper curve in the taper-curve's  own object-space.
As shown, the bevel can be mapped to less than the full extent of the curve, and there are various settings for the interpolation of the mapping from point to
point.
But, adjusting the number of subdivisions in the bevelled curve to capture, not only the curvature along its length, but also the variation in its radius, can be a bit fiddly.